Robert Tracinski keeps it simple. There are three main requirements, he says.
1) A clear understanding of the temperature record…. [that is] a long-term temperature record that allows us to isolate what the normal baseline is, so we know what natural variation looks like and we can identify any un-natural, man-made effect.
That would have to be an untampered-with long-term temperature record.
2) A full understanding of the underlying physical mechanisms…. The glibbest thing said by environmentalists—and proof that the person who says it has no understanding of science—is that human-caused global warming is “basic physics” because we know carbon dioxide is a greenhouse gas. Carbon dioxide is a very weak greenhouse gas and there is no theory that claims it can cause runaway warming all on its own. The warmists’ theory requires feedback mechanisms that amplify the effect of carbon dioxide. Without that, there is no human-caused global warming. But those feedback mechanisms are dubious, unproven assumptions…. The immense, untamed complexity of the climate is reflected in the poor performance of computerized climate models, which leads us to our last major hurdle in proving the theory of global warming.
Correlation is not causality. But the models can’t even show correlation! Which leads to …
3) The ability to make forecasting models with a track record of accurate predictions over the very long term…. It’s pretty clear that scientists aren’t any good yet at making global climate forecasts. Current temperatures are at or below the low range of all of the climate models. Nobody predicted the recent 17-year-long temperature plateau. And while they can come up with ad hocexplanations after the fact for why the data don’t match their models, the whole point of a forecast is to be able to get the right answer before the data comes in.
Given the abysmal record of climate forecasting, we should tell the warmists to go back and make a new set of predictions, then come back to us in 20 or 30 years and tell us how these predictions panned out. Then we’ll talk.
Read the whole piece: What It Would Take to Prove Global Warming – Robert Tracinski, THE TRACINCKI LETTER